Insights into the interfacial carrier behaviour of copper ferrite ( CuFe2O4) photoanodes for solar water oxidation

Designing efficient yet robust photoanodes for water oxidation stands out as a major bottleneck in the realization of a feasible photoelectrochemical tandem cell for solar water splitting. Spinel copper ferrite (CuFe2O4) has been recently reported as a potential candidate photoanode, exhibiting an extended light absorption (band gap of 1.9 eV) with respect to traditional metal oxides. However, limiting factors dictating the poor performance (0.5 mA cm(-2) at 1.6 V vs. RHE) remain unclear. Here, CuFe2O4 thin-film photoanodes were examined using frequency-dependent electrochemical techniques, namely photoelectrochemical impedance spectroscopy (PEIS) and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS), to provide a detailed description of the photogenerated charge carrier behaviour under operational conditions. Results evidenced a strong Fermi level pinning during oxygen evolution caused by the accumulation of surface intermediates and a relatively slow rate of charge transfer (k(tran) approximate to 5 s(-1)). Moreover, the short hole diffusion length (L-p approximate to 4 nm) and the low charge collection efficiency (below 10%) further prevent efficient charge extraction. Overall, these findings point towards the need of both film nanostructuring and surface engineering to further advance this photoanode.


Published in:
Journal Of Materials Chemistry A, 7, 4, 1669-1677
Year:
Jan 28 2019
Publisher:
Cambridge, ROYAL SOC CHEMISTRY
ISSN:
2050-7488
2050-7496
Keywords:
Laboratories:




 Record created 2019-06-18, last modified 2020-04-20


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